New Azepine-Furan Spirocyclic Structures in the Reaction of 4-Aroyl-1,2-dihydrobenzo[d]azepines and 2-Aroyl-4,5-dihydrophenanthreno[1,2-d]azepine with Formaldehyde

4-Aroyl-1,2-dihydrobenzo[d]azepines, as well as their phenanthro[1,2-d]azepine keto analogs, under the action of formaldehyde in the presence of acid-base catalysts, can undergo diastereoselective transformation into spirocyclic systems, containing two spiro-fused hetero rings – tetrahydroazepine and bifunctionalized tetrahydrofuran. This transformation is provided by a combination of azepine-azepine recyclization of substrates followed by spirocyclization of its products.